Various materials which are contained in exhaust gas which is discharged from a diesel engine of an automobile are a cause of air pollution, and have generated various environmental problems until now. Particularly, it is said that particulate matter (PM) which is contained in the exhaust gas is a cause of the occurrence of allergic symptoms such as asthma or hay fever.
In general, in a diesel engine for an automobile, a sealing type ceramic honeycomb structure (DPF: Diesel Particulate Filter) is used in order to collect the particulate matter. In the honeycomb structure, both ends of a cell (gas passage) of the ceramic honeycomb structure are sealed in a checker pattern, and particulate matter is collected when the exhaust gas passes through micropores in partitions of the cell (for example, refer to PTLs 1 and 2).